Nordgren, a professor of astronomy and physics at the University of Redlands in California, pegs his early interest in astronomy to his suburban-Portland grade school principal, who happened to be the uncle of astronaut Bonnie Dunbar. Mr. Dunbar used his connections to bring NASA folks to the school for talks. Nordgren decided then that he wanted to be an astronaut, too. Then he was amazed by Carl Sagan’s TV series.

“When I saw Cosmos I realized why I wanted to be an astronaut, or if not an astronaut, to be an astronomer,” Nordgren said.

Coincidentally, Nordgren attended graduate school at Cornell University when Sagan was on the faculty. He never took a class from Sagan, but in one of his first teaching gigs Jeremy Sagan, Carl’s son, was in Nordgren’s class. He said Jeremy sat in the front row, asked a lot of questions, and then talked over the lectures with his famous dad. No pressure there.

“I learned to be on my toes!” Nordgren joked.

Nordgren’s posters like this one for Chaco Culture National Historical Park help call attention to the importance of dark night skies in the parks.

A couple of events inspired Nordgren’s work in the national parks, which includes marvelous photography and a series of travel posters based on the style of the 1930s WPA graphics. The first was a visit to Palomar Observatory.

“My very first telescope was an eight-inch Celestron my father bought for me when I graduated from college,” Nordgren recalled. “My second telescope was the Palomar 200-inch” which he used in research about dark matter in spiral galaxies. When he returned 10 years later he was taken aback by the increased light pollution fueled by a housing boom in the area.

“It had been like a tidal wave of light had just swept out around the mountain,” he said. “It was stunning just how bad the skies now were at Palomar.”

Shortly after that trip, Nordgren celebrated gaining tenure by taking a trip to Yosemite National Park and attended an evening ranger talk about astronomy.

“For many, many people this was the first time they had seen a night sky, a truly pristine night sky,” Nordgren marveled.

He decided to spend an upcoming sabbatical in the National Park system helping rangers develop programs for park visitors to experience the night sky. He spent time in a dozen different parks over the course of 14 months, and came to realize that the preservation of the land that prevents development in the parks also, almost by accident, preserves the precious resource of truly dark skies. It’s a growing part of the appeal of the parks, articulated by the slogan “Half the park is after dark.”

“In those parks that offer night-sky programs the attendance they have is equal to if not better than the next two types of programs added together,” Nordgren noted. “Far and away these are the most popular ranger programs that are offered.”

Nordgren’s Mars poster

Much of Nordgren’s work is to link what people can see in the sky to what they see in the national parks. For example, he compares Mars to parks in the American Southwest; both Earth and the Red Planet have similar geology and chemistry. Yellowstone National Park has numerous geysers, similar to those on Saturn’s icy moon Enceladus.

“People paid attention to the sky, people have been doing that for centuries, millennia,” Nordgen said. “Unfortunately we’ve made it tremendously difficult to keep doing that.” As evidence he showed a photo of the sky above Chaco, which is still impressively dark and starry, but all around light pollution is encroaching from the cities of Gallup, Crownpoint, Albuquerque, and a nearby coal mine. Thus a big part of his aim is to get communities near the parks to recognize that the night sky is an attraction, and to encourage them to be good stewards of the dark sky. His spiel goes just as well for any city, regardless of its proximity to a national park.

“All that light that shines above the horizon doesn’t do anything useful,” Nordgren said. “So why are we lighting up the sky? There is nothing we need fear up there, so why are we paying for that light? Why are we generating that light? Why are we burning the natural resources to create that light?”

There really aren’t great answers to those questions, and Nordgren said the solutions are within reach.

“This can be a win-win situation for all of us,” he said. “We can get the stars back, we can save money, we can save natural resources. It really doesn’t have to be stars versus safety.”